.TH SLAPO-CONSTRAINT 5 "RELEASEDATE" "OpenLDAP LDVERSION"
.\" Copyright 2005-2006 Hewlett-Packard Company
.\" Copyright 2006-2024 The OpenLDAP Foundation All Rights Reserved.
.\" Copying restrictions apply.  See COPYRIGHT/LICENSE.
.\" $OpenLDAP$
.SH NAME
slapo\-constraint \- Attribute Constraint Overlay to slapd
.SH SYNOPSIS
ETCDIR/slapd.conf
.SH DESCRIPTION
The constraint overlay is used to ensure that attribute values match
some constraints beyond basic LDAP syntax.  Attributes can
have multiple constraints placed upon them, and all must be satisfied
when modifying an attribute value under constraint.
.LP
This overlay is intended to be used to force syntactic regularity upon
certain string represented data which have well known canonical forms,
like telephone numbers, post codes, FQDNs, etc.
.LP
It constrains only LDAP \fIadd\fP, \fImodify\fP and \fIrename\fP commands
and only seeks to control the \fIadd\fP and \fIreplace\fP values
of \fImodify\fP and \fIrename\fP requests.
.LP
No constraints are applied for operations performed with the
.I relax
control set.
.SH CONFIGURATION
These
.B slapd.conf
options apply to the constraint overlay. They should appear after the
.B overlay
directive.
.TP
.B constraint_attribute <attribute_name>[,...] <type> <value> [<extra> [...]]
Specifies the constraint which should apply to the comma-separated
attribute list named as the first parameter.
Eight types of constraint are currently supported -
.BR regex ,
.BR negregex ,
.BR size ,
.BR count ,
.BR uri ,
.BR neguri ,
.BR set ,
and
.BR negset .

The parameter following the
.B regex
or
.B negregex
type is a Unix style regular expression (See
.BR regex (7)
). The parameter following the
.B uri
or
.B neguri
type is an LDAP URI. The URI will be evaluated using an internal search.
It must not include a hostname, and it must include a list of attributes
to evaluate.

The parameter following the
.B set
or
.B negset
type is a string that is interpreted according to the syntax in use
for ACL sets.  This allows one to construct constraints based on the contents
of the entry.

The 
.B size
type can be used to enforce a limit on an attribute length, and the
.B count
type limits the number of values of an attribute.

Extra parameters can occur in any order after those described above.
.RS
.TP
.B <extra> : restrict=<uri>
.RE

.RS
This extra parameter allows one to restrict the application of the corresponding
constraint only to entries that match the
.IR base ,
.I scope
and
.I filter
portions of the LDAP URI.
The
.IR base ,
if present, must be within the naming context of the database.
The
.I scope
is only used when the
.I base
is present; it defaults to
.BR base .
The other parameters of the URI are not allowed.
.RE

.TP
.B constraint_allowempty FALSE | TRUE
Historically,
.B slapo-constraint
rejected Modify/Add requests with an empty sequence of modifications. This was
not intentional and if this option is
.BR TRUE ,
such modifications will be allowed so long as they are otherwise valid.
The default is
.B FALSE
to maintain backwards compatibility.

.LP
Any attempt to add or modify an attribute named as part of the
constraint overlay specification which does not fit the 
constraint listed will fail with a
LDAP_CONSTRAINT_VIOLATION error.
.SH EXAMPLES
.LP
.RS
.nf
overlay constraint
constraint_attribute jpegPhoto size 131072
constraint_attribute userPassword count 3
constraint_attribute mail regex ^[[:alnum:]]+@mydomain.com$
constraint_attribute mail negregex ^[[:alnum:]]+@notallowed.com$
constraint_attribute title uri
  ldap:///dc=catalog,dc=example,dc=com?title?sub?(objectClass=titleCatalog)
constraint_attribute cn neguri
  ldap:///ou=People,dc=example,dc=com?cn,sn?sub?(objectClass=inetOrgPerson)
constraint_attribute cn,sn,givenName set
  "(this/givenName + [ ] + this/sn) & this/cn"
  restrict="ldap:///ou=People,dc=example,dc=com??sub?(objectClass=inetOrgPerson)"
.fi

.RE
A specification like the above would reject any
.B mail
attribute which did not look like
.BR "<alphanumeric string>@mydomain.com"
or that looks like
.BR "<alphanumeric string>@notallowed.com" .
It would also reject any
.B title
attribute whose values were not listed in the
.B title
attribute of any
.B titleCatalog
entries in the given scope. (Note that the
"dc=catalog,dc=example,dc=com" subtree ought to reside
in a separate database, otherwise the initial set of
titleCatalog entries could not be populated while the
constraint is in effect.)
With the type "neguri" (negated "uri"), it would
ensure uniqueness of one (or more) attributes against one (or
more) other attributes. A specification like the above
would reject any
.B cn
attributes whose
.B any
values
.B was already listed
in another
.B cn
or
.B sn
attributes of any
.B inetOrgPerson
entries in the given scope.
Finally, it requires the values of the attribute
.B cn
to be constructed by pairing values of the attributes
.B sn
and 
.BR givenName ,
separated by a space, but only for entries derived from the objectClass
.BR inetOrgPerson .
Should the type "negset" have been used instead of "set", the
condition would have been reversed.
.RE
.SH FILES
.TP
ETCDIR/slapd.conf
default slapd configuration file
.SH SEE ALSO
.BR slapd.conf (5),
.BR slapd\-config (5),
.SH ACKNOWLEDGEMENTS
This module was written in 2005 by Neil Dunbar of Hewlett-Packard and subsequently
extended by Howard Chu and Emmanuel Dreyfus.
.so ../Project
